M4 Hex Nut - A4 Grade A4 grade stainless steel has a greater corrosion resistance than A2 in certain environments. It is often used for Marine applications especially when coming into direct contact with salt water Where: e = point to point m = thickness s = across flats d = Thread e - 7.66 mm (min) m - 2.9 mm (min) s - 7 d - M4 Thread Pitch - 0.7 mm DIN934